The GUI inside the app disconnects and stops working

// RemoteXY select connection mo.de and include library 
#define REMOTEXY_MODE__SOFTSERIAL
#include <SoftwareSerial.h>
#include <RemoteXY.h>

// RemoteXY connection settings 
#define REMOTEXY_SERIAL_RX 2
#define REMOTEXY_SERIAL_TX 3
#define REMOTEXY_SERIAL_SPEED 9600


// RemoteXY configurate  
#pragma pack(push, 1)
uint8_t RemoteXY_CONF[] =
  { 255,4,0,2,0,128,0,8,8,0,
  2,0,9,10,18,8,2,26,31,31,
  79,78,0,79,70,70,0,5,16,53,
  13,42,42,2,26,31,4,0,6,26,
  10,30,2,26,129,0,56,4,35,4,
  13,68,105,114,101,99,116,105,111,110,
  97,108,32,67,111,110,116,114,111,108,
  0,129,0,11,5,14,4,13,67,111,
  110,116,114,111,108,0,129,0,5,25,
  12,4,13,83,112,101,101,100,0,65,
  4,30,11,5,5,66,0,28,31,14,
  25,2,26,129,0,20,25,30,4,13,
  68,105,115,116,97,110,99,101,32,71,
  97,117,103,101,0 };
  
// this structure defines all the variables of your control interface 
struct {

    // input variable
  uint8_t switch_1; // =1 if switch ON and =0 if OFF 
  int8_t joystick_1_x; // =-100..100 x-coordinate joystick position 
  int8_t joystick_1_y; // =-100..100 y-coordinate joystick position 
  int8_t slider_1; // =0..100 slider position 

    // output variable
  uint8_t led_1_r; // =0..255 LED Red brightness 
  int8_t level_1; // =0..100 level position 

    // other variable
  uint8_t connect_flag;  // =1 if wire connected, else =0 

} RemoteXY;
#pragma pack(pop)

int ddist=0, dist=0;

/////////////////////////////////////////////
//           END RemoteXY include          //
/////////////////////////////////////////////
/* defined the right motor control pins */ 
#define PIN_MOTOR_RIGHT_UP 7 
#define PIN_MOTOR_RIGHT_DN 6 
#define PIN_MOTOR_RIGHT_SPEED 10 

/* defined the left motor control pins */ 
#define PIN_MOTOR_LEFT_UP 5 
#define PIN_MOTOR_LEFT_DN 4 
#define PIN_MOTOR_LEFT_SPEED 9 

#define PIN_LED 13
#define TRIG A0
#define ECHO A1

/* defined two arrays with a list of pins for each motor */ 
unsigned char RightMotor[3] =  
  {PIN_MOTOR_RIGHT_UP, PIN_MOTOR_RIGHT_DN, PIN_MOTOR_RIGHT_SPEED}; 
unsigned char LeftMotor[3] =  
  {PIN_MOTOR_LEFT_DN, PIN_MOTOR_LEFT_UP, PIN_MOTOR_LEFT_SPEED}; 

/* 
   speed control of the motor 
   motor - pointer to an array of pins 
   v - motor speed can be set from -100 to 100 
*/ 
void Wheel (unsigned char * motor, int v) 
{ 
  //if (v>100) v=100; 
  //if (v<-100) v=-100; 
  //if (dist>=60) RemoteXY.slider_1=0;
  if (v>0) { 
    digitalWrite(motor[0], HIGH); 
    digitalWrite(motor[1], LOW); 
    analogWrite(motor[2], RemoteXY.slider_1); //v*2.55
  } 
  else if (v<0) { 
    digitalWrite(motor[0], LOW); 
    digitalWrite(motor[1], HIGH); 
    analogWrite(motor[2], RemoteXY.slider_1); //(-v)*2.55
  } 
  else { 
    digitalWrite(motor[0], LOW); 
    digitalWrite(motor[1], LOW); 
    analogWrite(motor[2], 0); 
  } 
} 

void setup() 
{
  /* initialization pins */
  pinMode (PIN_MOTOR_RIGHT_UP, OUTPUT); 
  pinMode (PIN_MOTOR_RIGHT_DN, OUTPUT); 
  pinMode (PIN_MOTOR_LEFT_UP, OUTPUT); 
  pinMode (PIN_MOTOR_LEFT_DN, OUTPUT);
  pinMode(PIN_LED, OUTPUT);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  /* initialization module RemoteXY */
  RemoteXY_Init(); 
  // TODO you setup code
}

void loop() 
{ 
  /* event handler module RemoteXY*/
  RemoteXY_Handler();

  /* manage LED pin*/
  //digitalWrite(PIN_LED, (RemoteXY.switch_1==0)?LOW:HIGH);

  if (RemoteXY.switch_1==0) {
    /* LED in arduino*/
    digitalWrite(PIN_LED, LOW);
    /* LED in app */
    RemoteXY.led_1_r = 0;
  }
  else {
    /* LED in arduino*/
    digitalWrite(PIN_LED, HIGH);
    /* LED in app */
    RemoteXY.led_1_r = 255;
    /* senses the distance from obstacles */
    getDistance();
    /* manage the right motor */ 
    Wheel (RightMotor, RemoteXY.joystick_1_y - RemoteXY.joystick_1_x); 
    /* manage the left motor */ 
    Wheel (LeftMotor, RemoteXY.joystick_1_y + RemoteXY.joystick_1_x);
  }
  // TODO you loop code
  // use the RemoteXY structure for data transfer
}

void getDistance() 
{
  digitalWrite(TRIG,LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG,HIGH);
  delayMicroseconds(2);
  digitalWrite(TRIG,LOW);
  dist=pulseIn(ECHO,HIGH);
  dist=dist*.0178;
  if(dist>20){
    RemoteXY.level_1 = 0;
  }
  else {
    dist = ((((dist/0.2)-100)*(-1))+10);
    //ddist = dist;
    if (dist>=80) dist+=20;
    RemoteXY.level_1 = dist;
  }
  delay(10);
}